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Biomedical subjects

R Liu

Publications and source records attributed to R Liu.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Imaging evaluation and interventional therapy of hepatic metastases from small intestinal leiomyosarcoma].

OBJECTIVE: To evaluate the imaging appearances and the short-term curative effect of hepatic metastases from small intestine leiomyosarcoma treated by interventional methods. METHODS: Seven cases with 46 lesions of hepatic metastases from small intestinal leiomyosarcoma were analyzed retrospectively. The diameters of the metastases were from 2 cm to 18 cm. CT triphasic scan and hepatoarterial angiography were performed in all cases. The interventional therapy methods included transcatheter arterial chemoembolization (TACE) (all 7 cases), percutaneous left subclavian artery port-catheter system implantation (PCS) (1 case). Three cases were also treated with percutaneous tumor necrosis drainage (PTND) because of obvious liquefaction necrosis within the tumor. RESULTS: The lesions were substantial occupation and some were mixed density with cystic component. The cystic component increased in the larger tumor. The hepatic metastases were enhanced remarkably during the hepatic arterial-dominant phase scan and had abundant tumor vascular and tumor stain on hepatoarterial angiography. The size of tumor in 4 cases was reduced after TACE. The tumor in the patient who was treated with PCS had no changed. The size of the tumor in 3 cases was slightly enlarged. The tumors in the 3 patients treated with PTND were reduced remarkably. CONCLUSIONS: The predominant blood-supply of the hepatic metastases from small intestinal leiomyosarcoma is the hepatic artery abundant in blood vessels. TACE, PCS and PTND are effective methods to treat hepatic metastases from small intestinal leiomyosarcoma.

Angiography↗
PubMed2001

[Study on effect of delivery way on thyrotropin levels in pregnant women and their newborns].

OBJECTIVE: To investigate the effect on thyrotropin (TSH) levels of pregnant women and their newborns in different delivery ways. METHODS: The serum TSH levels of 213 pregnant women and the umbilical cord blood TSH levels of their newborns (140 cases from normal vaginal delivery, 38 cases from cesarean section, 35 cases from low forceps delivery) were tested by immunoradiometric assay. Urinary iodine was detected from pregnant women before delivery. RESULTS: In pregnant women, the mean serum level of TSH in the forceps group [(4.13 +/- 0.69) mU/L] was significantly higher than those of the normal birth group [(2.58 +/- 0.87) mU/L, P < 0.01] and the cesarean section group [(2.81 +/- 0.45) mU/L, P < 0.01]. There was no difference in TSH level between the normal birth group and the cesarean section group. In newborns, the mean TSH level in the forceps group [(8.85 +/- 2.48) mU/L] was significantly higher than those of the normal birth group [(5.36 +/- 2.23) mU/L, P < 0.01] and the cesarean section group [(3.84 +/- 2.16) mU/L, P < 0.01]. The mean TSH level in the normal birth group was significantly higher than that of the cesarean section group (P < 0.05). The serum TSH levels of pregnant women were positively correlated with the umbilical cord blood TSH levels of their newborns in three groups. CONCLUSIONS: The contraction of uterus is the stimulus for the surge in TSH levels of pregnant women and their newborns after delivery. It's reliable that the TSH levels of newborns could be evaluated by monitoring the TSH levels of pregnant woman.

Adult↗
PubMed2001

[Determination and significance of serum markers for fibrosis in patients with chronic hepatitis].

OBJECTIVE: To find the relationship between serum levels of hyaluronic acid (HA), type III procollagen (PC III), laminin (LN), type IV collagen (IV-C) and hepatic fibrosis as well as to determine their value in clinical practice. METHODS: 2600 serum samples from chronic hepatitis patients were tested with RIA for fibrosis indexes assays including HA, PC III, LN and IV-C. 280 of the patients with serum samples taken had liver biopsy performed and the biopsy material was examine pathomorphologically. Fibrosis indexes were compared according to inflammation grade, fibrosis stage and chronic hepatitis degree. RESULTS: In the 2600 serum samples from chronic hepatitis patients, fibrosis indexes (including HA, PC III, LN and IV-C) had significant correlation with inflammation grade, fibrosis stage and the degree of chronic hepatitis (P < 0.01). The relating indexes to HA were 0.544, 0.548, 0.468 respectively, to PC III 0.495, 0.424, 0.335 respectively, to LN 0.214, 0.204, 0.184 and to IV-C were 0.464, 0.404, 0.412 respectively. CONCLUSION: Serum fibrosis indexes are fairly well correlated with the inflammation grade, fibrosis stage and the degree of chronic hepatitis. However, as diagnostic markers, they must be combined with liver function, ultrasonography and clinical features.

Adolescent↗
PubMed2001

[Response of keloid fibroblasts to the effect of tumor necrosis factor-alpha(TNF-alpha)].

OBJECTIVE: To investigate the biologic behavior of keloid fibroblasts and the pathogenesis of keloid. METHODS: Human dermal fibroblasts cultured from normal skin and keloid were treated with tumor necrosis factor-alpha(TNF-alpha) for 48 hours at 10(3) U/ml and 10(4) U/ml. Collagen production by fibroblasts was assessed by 3H-proline in corporation into pepsin-resistant, precipitated extracellular collagenous protein. RESULTS: TNF-alpha caused a concentration-dependent reduction in collagen production in normal dermal fibroblasts. Treatment with TNF-alpha at 10(3) U/ml significantly reduced the collagen synthesis in keloid fibroblasts (P < 0.01). However, the collagen synthesis in keloid fibroblasts did not further decreased after exposure to TNF-alpha at 10(4) U/ml. CONCLUSIONS: Keloid fibroblasts may remain less sensitive to the inhibitory effects of TNF-alpha on collagen synthesis to a certain extent.

Collagen↗
PubMed2001

[Biosorption of heavy metals by bacteria isolated from activated sludge].

In this paper, biosorption efficiency of heavy metals by bacteria isolated from activated sludge was tested. It was shown that Pseudomonas pseudoalcaligenes and Micrococcus luteus GC subgroup B had high biosorption capacities for Cu(II) and Pb(II) ions. The adsorption of the two ions on Pseudomonas pseudoalcaligenes and Micrococcus luteus GC subgroup B exhibited Langmuir adsorption behavior with regression coefficient of 0.99. The pH value was the most important effect factor on biosorption of metal ions. The biosorption kinetic curves of Cu(II) and Pb(II) ions by cells showed two processes: rapid sorption on cell surface and slowly longer-term transformation into cells. Cu(II) ion can be desorbed effectively from cells of Micrococcus luteus GC subgroup B.

Absorption↗
PubMed2001

[Activation of NF-kappa B induced by stretching and the gene expression of beta-MHC regulated by NF-kappa B in cardiac myocytes].

OBJECTIVE: To determine the mechanism of reexpression of beta-MHC gene caused by the stimulation of stretch. METHODS: The specimens were taken from the 1-, 2- and 3-day old SD rats. Immunohistochemical method was applied to observe the activation of NF-kappa B in stretched cardiac myocytes cultured on the silicon membrane, and then with the system of image analysis, the beta-MHC protein content was detected in four groups where NF-kappa B was activated or not activated, respectively. RESULTS: NF-kappa B was activated significantly by stretching cardiac myocytes for five hours. The beta-MHC protein content in stretched myocytes increased significantly, compared with that in the control myocytes, NAC-treated myocytes, and stretch-treated myocytes in the presence of NAC. CONCLUSION: The above data demonstrate that NF-kappa B signaling system is involved in regulating the stretch-induced gene expression of beta-MHC.

Animals↗
PubMed2001

[The paraoxonase Gln-Arg192 polymorphism in patients with coronary heart disease in Chinese population].

OBJECTIVE: To investigate the 192 Gln-Arg polymorphism of paraoxonase (PON) gene and its relationship with serum lipids levels in patients with coronary heart disease in Chinese population. METHODS: The genotype and allele frequency of paraoxonase gene 192 Gln-Arg polymorphism was assayed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Serum lipids were measured by enzymatic kits in 118 CHD patients and 128 healthy subjects whose fasting serum TG levels were < 1.82 mmol/L and TC levels < 6.2 mmol/L from a population of Chinese Han nationality in Chengdu area. RESULTS: Both in CHD group and control group, the QR genotype of PON gene was the major one, and its frequencies were 0.578 and 0.525 respectively. No differences were found in PON gene Gln-Arg polymophism in the CHD group when compared with the control group. The frequency of R allele of PON gene in Chinese was significant higher than that in European and American Caucasians (0.51 vs. 0.26-0.31, P < 0.01) and Indian (0.51 vs. 0.17, P < 0.01), and significantly lower than that in Japanese (0.51 vs. 0.65, P < 0.01). CONCLUSION: These results suggested that the Gln-Arg192 polymorphism of the PON1 gene was not associated with coronary heart disease in Chinese population.

Aged↗
PubMed2001

[Detection of telomerase activity in laryngeal carcinoma and the association between telomerase activity and lymphatic metastasis].

OBJECTIVE: To investigate the telomerase activity in human laryngeal squamous cell carcinomas (LSCC) and the association between telomerase activity and lymphatic metastasis. METHOD: Telomerase activity was determined in 47 specimens of LSCC and 10 specimens of laryngeal inflammatory polyps using PCR-ELISA. RESULT: Telomerase activity was detected in 39 of 47 (83%) LSCC, but was not detected in all 10 laryngeal inflammatory polyps. There were significant differences between them (P < 0.01). Telomerase activation in LSCC with positive cervical lymph node involvement appeared to be higher (13 out of 13 cases, 100%) than in LSCC with negative cervical lymph node involvement (26 out of 34, 76.47%), (P < 0.05). CONCLUSION: Telomerase is activated frequently in LSCC and may become a biomarker of LSCC. The detection of telomerase activity in LSCC may have some value for predicting metastasis potential and prognosis and can guide the clinical practices applying selective neck dissection.

Adult↗
PubMed2001

[Chemical constituents from the root of Rubus chroosepalus].

AIM: To investigate the chemical constituents of Rubus chroosepalus Focke. METHODS: The methanol extracts were suspended in H2O and then extracted with EtOAc. Column chromatography was used for separation and purification, while spectral analysis was used for identification. RESULTS: Seven compounds were isolated and identified as 2 alpha, 3 beta-dihydroxy-urs-12, 19-dien-23, 28-oic acid (I), 2 alpha, 3 beta, 23-trihydroxy-urs-12,18-dien-28-oic acid (IIa), 2 alpha, 3 beta, 23-trihydroxy-urs-12,19-dien-28-oic acid (IIb), 2 alpha, 3 alpha-dihydroxy-urs-12,18-dien-28-oic acid (IIIa), 2 alpha, 3 alpha-dihydroxy-urs-12,19-dien-28-oic acid (IIIb), and the acetonide of IIIa and IIIb (IVa and IVb). CONCLUSION: I was found to be a new pentacyclic triterpenoid acid.

Molecular Structure↗
PubMed2001

[Apolipoprotein C III gene Sst I polymorphism in patients with endogenous hypertriglyceridemia in Chinese population].

OBJECTIVE: To investigate the apoC III gene Sst I polymorphism and its relationship with serum lipids and apolipoproteins (apo) levels in patients with endogenous hypertriglyceridemia in Chinese population. METHODS: The genotype and allele frequency of apoC III gene Sst I polymorphism was assayed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Serum lipids were measured by enzymatic kits and apolipoproteins A I, A II, B100, C II, C III and E were measured by RID kits developed by Apolipoprotein Research Unit of WCUMS in 176 HTG patients whose fasting serum TG levels were > or = 2.26 mmol/L and in 199 healthy subjects whose fasting serum TG levels were < 1.82 mmol/L and TC levels < 6.2 mmol/L from a population of Chinese Han nationality in Chengdu area. RESULTS: In both HTG group and control group, S1 allele was the major allele and homozygous S1S1 genotype was the most frequent one. The frequency of S2 allele was significantly higher than that reported in Caucasians (0.289 vs 0.06-0.16, P < 0.05). No differences were found in apoC III gene Sst I polymophism in the HTG group when compared with the control group (0.287 vs 0.289, P > 0.05). The genotype of S2S2 was not associated with higher TG and apolipoproteins levels when compared with the genotypes of S1S1 and S1S2 (P > 0.05). CONCLUSION: These results suggest that the Sst I polymorphism of the apoC III gene was not associated with endogenoushypertriglyceridemica in Chinese population.

Adult↗
PubMed2001

[Surgery of the skull base assisted by sinus endoscope].

OBJECTIVE: To explore the feasibility and clinical value of the endoscopic operations around the skull base. METHODS: A retrospective study was made of 44 cases treated by endoscopic operations. Twenty-five cases underwent intranasal endoscopic operations. RESULTS: Forty of 44 cases were cured by one-stage surgery. One case of cartridge foreign body clamped in clivus was not successfully removed; only window operation and puncture biopsy were done in another case of pituitary adenoma; high cranial pressure has not been completely reduced after operation in the third case with relapsing craniopharyngioma a companied with obstructive hydrocephalus. One case of sphenoidal malignant adenoma involving saddle based and extended laterally was partly resected. Complications were follows: cerebrospinal fluid rhinorrhea in 2 cases, diabetes insipidus in 1 case, all of them were cured by conservative treatment; nasal septum perforation in 1 case, without any treatment. CONCLUSIONS: The endoscopic skull base surgery by intranasal approach is feasibility. Intranasal approach has direct path, slight wound and no wound in face. Combined with operation microscope, sinus endoscope can make up for its limits.

Endoscopy↗
PubMed2000

Identification of a noncanonical signal for transcription of a novel subgenomic mRNA of mouse hepatitis virus: implication for the mechanism of coronavirus RNA transcription.

Subgenomic RNA transcription of coronaviruses involves the interaction between the leader (or antileader) and the intergenic (IG) sequences. However, it is not clear how these two sequences interact with each other. In this report, a previously unrecognized minor species of subgenomic mRNA, termed mRNA5-1, was identified in cells infected with mouse hepatitis virus (MHV) strains JHM2c, JHM(2), JHM(3), A59, and MHV-1. Sequence analysis revealed that the leader-body fusion site of the mRNA is located at approximately 150 nucleotides (nt) downstream of the consensus IG sequence for mRNA 5 and did not have sequence homology with any known IG consensus sequences. To determine whether this sequence functions independently as a promoter, we cloned a 140-nt sequence (from approximately 70 nt upstream to approximately 70 nt downstream of the fusion site) from viral genomic RNA and placed it in front of a reporter gene in the defective-interfering (DI) RNA-chloramphenicol acetyltransferase (CAT) reporter vector. Transfection of the reporter RNA into MHV-infected cells resulted in synthesis of a CAT-specific subgenomic mRNA detected by reverse transcription-polymerase chain reaction (RT-PCR). The strength of this promoter was similar to that of the IG7 (for mRNA 7) as measured by the CAT activity. Deletion analysis showed that the sequence as few as 13 nt was sufficient to initiate mRNA transcription, while mutations within the 13-nt abolished mRNA transcription. In vitro translation study confirmed that the envelope (E) protein was translated from mRNA5-1, which encodes the open reading frame (ORF) 5b at its 5'-end, indicating that mRNA5-1 is a functional message. Furthermore, when the ORF5b was replaced with the CAT gene and placed in the DI in the context of viral mini-genome, CAT was expressed not only from the first ORF of mRNA5-1 but also from the second and third ORF of mRNA5 and genomic DI RNA, respectively, suggesting that more than one mechanism is involved in regulation of ORF5b expression. Our findings thus support the notion that base-pairing between the leader (or antileader) and the IG is not the sole mechanism in subgenomic RNA transcription.

Animals↗
PubMed2000

Intrinsic fluorescence of the P-glycoprotein multidrug transporter: sensitivity of tryptophan residues to binding of drugs and nucleotides.

P-glycoprotein is a member of the ATP binding cassette family of membrane proteins, and acts as an ATP-driven efflux pump for a diverse group of hydrophobic drugs, natural products, and peptides. The side chains of aromatic amino acids have been proposed to play an important role in recognition and binding of substrates by P-glycoprotein. Steady-state and lifetime fluorescence techniques were used to probe the environment of the 11 tryptophan residues within purified functional P-glycoprotein, and their response to binding of nucleotides and substrates. The emission spectrum of P-glycoprotein indicated that these residues are present in a relatively nonpolar environment, and time-resolved experiments showed the existence of at least two lifetimes. Quenching studies with acrylamide and iodide indicated that those tryptophan residues predominantly contributing to fluorescence emission are buried within the protein structure. Only small differences in Stern-Volmer quenching constants were noted on binding of nucleotides and drugs, arguing against large changes in tryptophan accessibility following substrate binding. P-glycoprotein fluorescence was highly quenched on binding of fluorescent nucleotides, and moderately quenched by ATP, ADP, and AMP-PNP, suggesting that the site for nucleotide binding is located relatively close to tryptophan residues. Drugs, modulators, hydrophobic peptides, and nucleotides quenched the fluorescence of P-glycoprotein in a saturable fashion, allowing estimation of dissociation constants. Many compounds exhibited biphasic quenching, suggesting the existence of multiple drug binding sites. The quenching observed for many substrates was attributable largely to resonance energy transfer, indicating that these compounds may be located close to tryptophan residues within, or adjacent to, the membrane-bound domains. Thus, the regions of P-glycoprotein involved in nucleotide and drug binding appear to be packed together compactly, which would facilitate coupling of ATP hydrolysis to drug transport.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Regulation of beta 1 integrin-mediated adhesion by T cell receptor signaling involves ZAP-70 but differs from signaling events that regulate transcriptional activity.

Stimulation of the CD3/TCR results within minutes in an increase in T cell adhesion mediated by beta(1) integrins. The biochemical pathways that control CD3-mediated increases in beta(1) integrin-mediated adhesion remain poorly characterized. In this study, the role of the tyrosine kinase ZAP-70 in the regulation of beta(1) integrin activity by the CD3/TCR was investigated. CD3 stimulation did not increase beta(1) integrin-mediated adhesion of the ZAP-70-deficient Jurkat T cell line, P116, to the beta(1) integrin ligand fibronectin. Reintroduction of wild-type ZAP-70, but not a kinase-inactive variant, K369R, corrected the adhesive defect observed in P116 T cells. In addition, the kinase-inactive ZAP-70 mutant inhibited CD3-induced adhesion of primary human T cell blasts. Interestingly, a ZAP-70 mutant with a tyrosine to phenylalanine substitution at position 319 (Y319F) restored the adhesive defect in P116 T cells, even though Y319F ZAP-70 failed to fully reconstitute CD3-initiated NF-AT-dependent transcription and tyrosine phosphorylation of the LAT adapter protein. Finally, expression of mutants of LAT and the SLP-76 adapter protein that modulate CD3-mediated activation of an NF-AT reporter gene failed to block CD3-induced increases in beta(1) integrin-mediated adhesion. These observations support a model in which the tyrosine kinase activity of ZAP-70 kinase is critical for regulation of beta(1) integrin activity by CD3/TCR. However, the signaling events downstream of ZAP-70 that regulate CD3/TCR-mediated activation of beta(1) integrin function exhibit key differences when compared with the signaling pathways that regulate transcriptional events initiated by CD3/TCR stimulation.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Serotonin 5-HT(2) receptors activate local GABA inhibitory inputs to serotonergic neurons of the dorsal raphe nucleus.

The purpose of the present study was to characterize the synaptic currents induced by bath-applied serotonin (5-HT) in 5-HT cells of the dorsal raphe nucleus (DRN) and to determine which 5-HT receptor subtypes mediate these effects. In rat brain slices, 5-HT induced a concentration-dependent increase in the frequency of inhibitory postsynaptic currents (IPSCs) in 5-HT neurons recorded intracellularly in the ventral part of the DRN (EC(50): 86 microM); 5-HT also increased IPSC amplitude. These effects were blocked by the GABA(A) receptor antagonist, bicuculline (10 microM) and by the fast sodium channel blocker, TTX, suggesting that 5-HT had increased impulse flow in local GABAergic neurons. DAMGO (300 nM), a selective mu-agonist, markedly suppressed the increase in IPSC frequency induced by 5-HT (100 microM) in the DRN. A near maximal concentration of the selective 5-HT(2A) antagonist, MDL100,907 (30 nM), produced a large reduction ( approximately 70%) in the increase in IPSC frequency induced by 100 microM 5-HT; SB242,084 (30 nM), a selective 5-HT(2C) antagonist, was less effective ( approximately 24% reduction). Combined drug application suppressed the increase in 5-HT-induced IPSC frequency almost completely, suggesting involvement of both 5-HT(2A) and 5-HT(2C) receptors. Unexpectedly, the phenethylamine hallucinogen, DOI, a partial agonist at 5-HT(2A/2C) receptors, caused a greater increase (+334%) in IPSC frequency than did 5-HT 100 microM (+80%). This result may be explained by an opposing 5-HT(1A) inhibitory effect since the selective 5-HT(1A) antagonist, WAY-100635, enhanced the 5-HT-induced increase in IPSCs. These results indicate that within the DRN-PAG area there may be a negative feedback loop in which 5-HT induces an increase in IPSC frequency in 5-HT cells by exciting GABAergic interneurons in the DRN via 5-HT(2A) and, to a lesser extent, 5-HT(2C) receptors. Increased GABA tone may explain the previous observation of an indirect suppression of firing of a subpopulation of 5-HT cells in the DRN induced by phenethylamine hallucinogens in vivo.

Afferent Pathways↗
PubMed2000

1,25 dihydroxyvitamin D(3) activates sphingomyelin turnover in ROS17/2.8 osteosarcoma cells without sphingolipid-induced changes in cytosolic Ca(2+).

1,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] initiates the hydrolysis of sphingomyelin in ROS 17/2.8 osteosarcoma cells with the resultant generation of cell-associated ceramide. Increases in ceramide levels were detectable at 15 min and maximal one hour after exposure of cells to 1,25(OH)(2)D(3). Neither 1,25(OH)(2)D(3) nor exogenous ceramide elicited a change in cytosolic free Ca(2+) ([Ca(2+)](i)). Transient elevations in [Ca(2+)](i) were observed when cells were exposed to exogenous sphingosine, but there was no detectable conversion of ceramide to sphingosine in 1, 25(OH)(2)D(3)-treated cells. Ceramide also did not stimulate Ca(2+) uptake across ROS 17/2.8 cell plasma membranes. Collectively, these results suggest that 1,25(OH)(2)D(3) activates sphingomyelin turnover in ROS 17/2.8 osteosarcoma cells but that the sphingolipid metabolite ceramide is not responsible for 1,25(OH)(2)D(3)-induced activation of plasma membrane Ca(2+) channels.

Animals↗
PubMed2000

Cloning and characterization of a novel human class I histone deacetylase that functions as a transcription repressor.

Histone acetylation alters chromatin state by modifying lysines on histone and plays an important role in modulating gene transcription. A dynamic balance of histone acetylation/deacetylation is maintained by histone acetyltransferases and histone deacetylases. Emerging evidence suggests that a family of histone deacetylases may exist to regulate diverse cellular functions, including chromatin structure, gene expression, cell cycle progression, and oncogenesis. We describe here a novel human histone deacetylase, named HDAC8, cloned from human kidney. HDAC8 encodes 377 amino acid residues and shares extensive homology to several known HDACs, in particular a histone deacetylase from Arabidopsis thaliana. Northern blot analyses revealed that HDAC8 expression pattern for HDAC8 is distinct from that for HDAC1 and HDAC3, and expression of HDAC8 mRNA occurs in multiple organs including heart, lung, kidney, and pancreas. HDAC8 mRNA was also observed in several cell lines derived from cancerous tissues. When expressed in HEK293 cells, HDAC8 exhibited deacetylase activity toward acetylated histone, indicating that this protein is a bona fide histone deacetylase. Its histone deacetylase activity was inhibited by trichostatin and other known histone deacetylase inhibitors. Furthermore, active recombinant HDAC8 was expressed and purified from Escherichia coli. When ectopically expressed in cells, HDAC8 was found to be localized to the nucleus. Co-transfection experiments demonstrated that expression of HDAC8 repressed a viral SV40 early promoter activity. These results indicate that HDAC8 is a novel member of the histone deacetylase family, which may play a role in the development of a broad range of tissues and potentially in the etiology of cancer.

3T3 Cells↗